• Journal of Information Technology Services
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• v.12 no.2
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• pp.361-371
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• 2013

Public domain defect data sets, such as NASA data sets which are available from the NASA MDP and PROMISE repositories, make it possible to compare the results of different defect prediction models by using the same data sets. This means that repeatable and general prediction models can be built. However, some recent studies have raised questions about the quality of two versions of NASA data set, and made new cleaned data sets by applying their data cleaning processes. We find that there are two ways in the NASA MDP versions to determine the defectiveness of a module, 0 or 1, and the two results are different in some cases. This serious problem, to our knowledge, has not been addressed in previous studies. To handle this ambiguity problem, we define two kinds of module defectiveness and two conditions that can be used to determine the ambiguous cases. We meticulously analyze 5 projects among the 13 NASA projects by using our ambiguity analysis method. The results show that JM1 and PC4 are the best projects with few ambiguous cases.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.29B no.10
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• pp.59-68
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• 1992

In this paper, we proposed coordinator description and ambiguity on the hybrid controller for position/force control of robot manipulator. When the hybrid controller is desiged based on the PID control conception, the parameter sharing problem must be considered. However, selection problem of coordinate system on n-DOF robot manipulator control is unsolved. Moreover, contact force on object and change of shape make another problems. And it is very difficult to figure out the accurate mathematical model of manipulator on account of ambiguity and nonlinearity of actuator. Therfore, we design a new hybrid controller, FPID(Fuzzy PID). For verifying the validity of the controller, we tried computer simulation of this system. As a result, we can get remarkable improvement of overdamping and overshooting. Also we can solve compicance problem effectively. Furthermore, ambiguity problem is solved by adding control knowledge based compensator. So robust controller can be acheived, too.

• Journal of Advanced Navigation Technology
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• v.15 no.4
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• pp.502-509
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• 2011

It is necessary to resolve integer ambiguity in GPS carrier based precise positioning. If there is no signal blockage or cycle slip, the integer ambiguity does not changed. however, signal blockage and cycle slip occur frequently under real operational environment. under this situation, integer ambiguity maintenance is indispensable for continuity of navigation information. In this paper, a cycle slip free technique is proposed for simplifying integer ambiguity maintenance procedure. this technique tested with simulated carrier phase signal with cycle slip aided intentionally. As a result, the proposed technique can give navigation information continuously even if cycle slip is occured.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.705-708
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• 2010

Recently, HSRC (Half-Symbol-Rate-Carrier) OQPSK (Offset Quadrature Phase Shift Keying) signaling which reduces the bandwidth of transmitted signal for high-speed data communications has been introduced. Since the signal is based on QPSK modulation, it also has the characteristics of QPSK signal. This paper introduces architectures of the transceiver using differential coding to resolve the 4-phase ambiguity problem of the HSRC-QOPSK signaling for high-speed data communications. In addition, this paper proves the functionality of the transceiver with differential coding and shows the BER (bit-error-rate) performance of the transceiver by simulations.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.02a
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• pp.82-94
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• 2004

This paper addresses solutions to the challenges of carrier phase integer ambiguity resolution and cycle slip detection/identification, for maintaining high accuracy of an integrated GPS/Pseudolite/INS system. Such a hybrid positioning and navigation system is an augmentation of standard GPS/INS systems in localized areas. To achieve the goal of high accuracy, the carrier phase measurements with correctly estimated integer ambiguities must be utilized to update the system integration filter's states. The occurrence of a cycle slip that is undetected is, however, can significantly degrade the filter's performance. This contribution presents an effective approach to increase the reliability and speed of integer ambiguity resolution through using pseudolite and INS measurements, with special emphasis on reducing the ambiguity search space. In addition, an algorithm which can effectively detect and correct the cycle slips is described as well. The algorithm utilizes additional position information provided by the INS, and applies a statistical technique known as the cumulative-sum (CUSUM) test that is very sensitive to abrupt changes of mean values. Results of simulation studies and field tests indicate that the algorithms are performed pretty well, so that the accuracy and performance of the integrated system can be maintained, even if cycle slips exist in the raw GPS measurements.

• Journal of the Korea Convergence Society
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• v.10 no.1
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• pp.1-6
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• 2019

In this paper, we have studied a direction finding method of the radio signal by comparing the phase difference and its pattern from the uniform circular array antenna. In the phase comparison direction finding, if the length of the antenna baseline is longer than 0.5 wavelength of the incident signal, azimuth ambiguity occurs in which two or more azimuth angles are calculated in the same phase difference. The azimuthal ambiguity is removed by fusing the phase difference of the 5 antennas. The developed ambiguity elimination technology reduces the azimuth error where the antenna baseline is shorter than 1.236 wavelength in the uniform circular array with five antennas. This algorithm is very useful for the design of direction finder of an electronic information system.

• International Journal of Control, Automation, and Systems
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• v.4 no.3
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• pp.333-343
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• 2006

In this paper, the baseline-length information is directly modeled as a measurement for the Wald test, which speeds up the resolution convergence of the integer ambiguity of GPS carrier phase measurements. The convergent speed improvement is demonstrated using numerical simulation and real experiments. It is also shown that the integer ambiguities can be resolved using only four actual satellite measurements with very reasonable convergence speed, if the baseline-length information is used just like one additional observable satellite measurement. Finally, it is shown that the improvement of convergence speed of the Wald test is due to the increase of the probability ratio with the use of the baseline-length constraint.

• Journal of the Korea Society of Computer and Information
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• v.22 no.11
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• pp.117-124
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• 2017

The purpose of this study was to examine the factors influencing on Codependency of college students from Double ABCX model. This study examined the mediating relationship between boundary ambiguity, internal working model and psychological maladjustment, and then examined the moderating effects of Self-esteem, Social support and World view orientation. This study also examined the relationships of codependency with gender, enonomic level in college students. The results of the study are as follows. First, this study showed that codependency was related to economic level of college students. But it has not significant relationship with gender. Second, the moderating effects of Self-esteem, Social support and World view orientation was not significant. Third, mediating effects of Codependency on Boundary ambiguity, Internal working model and Psychological maladjustment were significant. This study suggested some theoretical and policy implications basing on this analytical results.

• Language and Information
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• v.7 no.2
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• pp.59-79
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• 2003

Coordination in natural language is often syntactically explained by the rule schema X \longrightarrow X′ and X", where X′ and X" refer to expressions of a like syntactic type. While this schema does explain a lot of instances of coordination, it is well known that this schema also gives rise to serious structural ambiguity, leading not only to numerous unintended interpretations but also to a high degree of unnecessary computational complexity. In order to identify intended interpretations, we need to take into account a number of clues at all the levels of morphology, syntax, semantics, and pragmatics/discourse. In this paper, we propose, with an accompanying data analysis, principles of symmetry and coherency for an effective and reasonable identification of intended interpretations from coordination-bearing sentences.

• Proceedings of the Korean Society for Language and Information Conference
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• 1995.02a
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• pp.121-126
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• 1995

A new method for Chinese word segmentation named Conditional F'||'&'||'BMM (Forward and Backward Maximal Matching) which incorporates both bigram statistics (ie., mutual infonllation and difference of t-test between Chinese characters) and linguistic rules for ambiguity resolution is proposed in this paper The key characteristics of this model are the use of: (i) statistics which can be automatically derived from any raw corpus, (ii) a rule base for disambiguation with consistency and controlled size to be built up in a systematic way.